Nobody who really knows would tell.

Can't assume a sealed indictment in a particular court applies to a particular case or person ('cause they are sealed).

We don't know if they even belong to Mueller. They probably don't, because DOJ discourages them unless the defendant is missing or a flight risk. In Mueller's case, we alreqdy know who is being investigated and none of them are going anywhere.

I wouldn't be surprised if he has a bunch of indictments just waiting for grand jury approval.

There would have to be a reason why the indictments were sealed, such as the danger of the defendant fleeing the jurisdiction if it is made public before his arrest.

I don't think there are any sealed indictments, unless they are indictments of a defendant who turned cooperating witness and is working undercover for the prosecutors.